The invention relates to punched document cards and more particularly to a reading machine for such cards.
The conventional IBM 80 column document card is rectangular in shape and has 80 columns and 12 rows for punching. The columns and rows respectively extend transversely and longitudinally of the card. The punched openings are ordinarily rectangular in shape and are one-eighth inch long extending transversely of the card. The rows are generally spaced 1/4 inch, center to center.
It has been recognized that a machine for operating on such cards shall preferably be of the serial type, that is, one in which the cards pass through the machine longitudinally of the card. A punched hole responsive starwheel for reading the punched holes in such a card need thus only be provided for each of the 12 rows of punched openings in the card rather than one for each of the 80 columns.
It has been proposed previously that such a machine include mechanism for serially moving each of the cards from the bottom of a deck of the cards; however, due to the alignment of the webs of adjacent punched openings in each of the rows, the webs of the lowermost card being fed interlock and tear with respect to the webs of the card immediately above the lowermost card in the deck.